Why is LDC built with old version of LDC

[Nicholas Wilson]

On Saturday, 20 July 2019 at 19:34:35 UTC, Dennis Cote wrote:
> I'm just curious if there is a good reason why LDC is built 
> with an old version of LDC? LDC reports the following using the 
> --version option
>
>  Jul 20 13:23:42 on ttys000
> Denniss-iMac:~ dennis$ ldc2 --version
> LDC - the LLVM D compiler (1.16.0):
>   based on DMD v2.086.1 and LLVM 8.0.0
>   built with LDC - the LLVM D compiler (1.12.0)
>   Default target: x86_64-apple-darwin18.6.0
>   Host CPU: skylake
>   http://dlang.org - http://wiki.dlang.org/LDC
>
> Why is version 1.16.0 built using version 1.12.0? Could the 
> build tools not bootstrap the compiler using 1.12.0, and then 
> recompile the source for version 1.16.0 using the version 
> 1.16.0 compiler built using the older compiler?

Probably because that corresponds to the minimum version that the 
frontend requires to build itself (which I think is 2.079). It 
definitely could be built with itself, theres nothing stopping 
that from happening.